reference data

ISCEV Standards require that centres use reference data (archaically, normative data) to define the typical, healthy limits of variability of electrophysiological parameters. The gold standard method for establishing reference limits requires prospective, direct sampling of reference subjects closely matched to a centre’s patient population and with at least 120 subjects per partition of clinical significance, e.g. sex. This is an onerous and costly process. International guidelines and recommendations outline alternative acceptable processes, including:

• Verification: quality checks to ensure safe local adoption of reference limits established elsewhere, perhaps requiring checks on at least 20 local reference subjects.
• Transference: modification of reference limits established using a differing technique (i.e. different ERG electrode type) requiring checks using both techniques on at least 40 local subjects, followed by verification.
• Indirect (patient) sampling: mathematical extraction of a 'health-related' sub-population from large patient datasets, used to calculate reference limits.

To support centres to use adequate quality reference data, ISCEV has collated here some references datasets. Users should be familiar with the relevant quality requirements before adopting any dataset, either collated here or elsewhere. ISCEV is not responsible for incorrect use of these or any other datasets.

For each dataset, two files are available. The first is a text file describing the metadata, i.e. details of subjects and recording, which may be a publication, and which may have summary data (e.g. calculated limits). The second, when available, is the raw, fully anonymised dataset, available via a public data depository.

USEFUL SOURCES

Horowitz GL, Clinical and Laboratory Standards Institute (CLSI) (2010) Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline–Third Edition. CLSI document EP28-A3c. Clinical and Laboratory Standards Institute, Wayne, PA

International Federation of Clinical Chemistry (1987) Approved Recommendation (1987) on the Theory of Reference Values. Part 5. Statistical Treatment of Collected Reference Values - Determination of Reference Limits. J Clinical Chem Clinical Biochem 25:645–656

Harris EK, Boyd JC (1995) Statistical bases of reference values in laboratory medicine. M. Dekker, New York

Horn PS, Pesce AJ (2005) Reference intervals: a user’s guide. AACC Press, Washington, DC

Budd JR, Durham AP, Gwise TE et al (2013) Measurement procedure comparison and bias estimation using patient samples; approved guideline. Clinical Laboratory Standards Institute, Wayne, PA

Davis, C.Q., Hamilton, R. Reference ranges for clinical electrophysiology of vision. Doc Ophthalmol 143, 155–170 (2021).https://doi.org/10.1007/s10633-021-09831

PATTERN REVERSAL VEP

Reference data for prVEP P100 amplitude and peak time (60’ and 15’ checkwidths) from 649 infants and children aged 2 weeks to 16 years. Note that data were acquired prior to publication of the current ISCEV VEP Standard. Metadata. Data.

FULLFIELD ERG